1. Technical Field
The present invention relates to a test device and a semiconductor integrated circuit device that has improved manufacturability.
2. Discussion of the Related Art
Static Random Access Memory (SRAM) is a type of semiconductor memory that, unlike Dynamic Random Access Memory (DRAM), does not have to be refreshed. SRAM is faster, but has less memory capacity than DRAM. Accordingly, SRAM is used where high bandwidth is a principle consideration. For example, SRAM may be used in a personal or laptop computer as a processor cache, or in a portable device such as a cellphone or handheld computer.
Static memory cells can be classified as thin film transistor (TFT) cells, full complementary metal oxide semiconductor (FCMOS) cells, etc. An FCMOS cell may include a plurality of pull-up transistors and pull-down transistors, which may form a latch, and a plurality of pass transistors may be used to access the latch.
As the integration density of semiconductor memory devices has increased, the size of memory cells and the size of metal contacts of the memory cells have decreased. The decrease in contact size can cause the metal contacts to be inaccurately patterned, thereby resulting in increased contact failures. Particularly, in the static memory cells, adjacent shared contacts may become electrically connected to each other. This electrical connection is referred to as a bridge.
To detect the occurrence of a bridge between adjacent shared contacts, nodes are connected to the respective adjacent shared contacts, and then, it is determined whether current flows between the nodes or not.
If there is current flow between the nodes, a determination may be made that a bridge has occurred between the adjacent shared contacts. However, there can be many reasons for why this bridge has occurred. For example, there could be a short-circuit between adjacent active regions, a short-circuit between a contact and a gate line, a short-circuit between nodes, and so on.
Therefore, there is a need to accurately determine the cause of current flow between adjacent shared contacts of a memory cell.